The present invention relates to an apparatus for producing and filling tubular bags formed from heat sealable foils.
Various embodiments of apparatus for producing filled tubular bags are known. All such known apparatus harbor the danger that during sealing of a filled bag, the upper portion of the resulting package will be tightly filled with air. It has therefore already been proposed to extract the air from the bags before the upper transverse seal is made. If this is done by means of a continuously operating blower, the drawback arises that the subatmospheric pressure produced increases the friction between the tube from which the bag is formed and the shaping pipe so that removal of the tube is made more difficult.
Swiss Pat. No. 554,258 issued July 26th, 1973, discloses the extraction of a protective gas from the end of the shaping pipe by means of a blower and the reintroduction of this gas into the dosaging device at the upper end of the fill pipe. However, the above-mentioned drawback again arises as a result of the continuously operating blower. Moreover, there exists the danger, when goods are handled which tend to form dust, that a certain quantity of the goods is carried along with the gas and must then be separated by means of a filter so as to prevent soiling of the blower and of the dosaging scales.